Improved soeew machine



H. J. HARWOOD.

SCREW MACHINE.

No. 65,567. Patented June 11, 1867.

.Zzwenr gotten tstss gaunt @ffi HARVEY J. HARWOOD, OF UTIGA, NEW YORK, ASSIGNOR THROUGH MESNE ASSIGNMENTS TO HIMSELF.

Letters Patent No. 65,567, dated June 11, 1867.

IMPROVED SCREW MACHINE.

Be it known that I, HARVEY J. HARWOOD, of Utica, in the county of Oneida, and State of New York, have invented a new and useful Improvement in" the Art of Manufacturing Screws commonly known as wood-screws.

In the manufacture of wood-screws the thread has been formed hitherto by removing the metal between the turns of the thread by means of dies or cutters.

By my invention the blank is rotated between rotating or reciprocating dies, suitably formed, and set in motion, by means of which the thread is impressed on the blank without removing any part of the metal.

And I do hereby declare that the following is a full, clear, and exact description of the construction and operation of these-id improvement, reference being had to the annexed drawings, making a part of this specification, in which Figure 1 is a sectionalvicw of the machine taken through the centre of the driving-shaftC on the line out, fig. 2.

Figure 2 is a perspective view of one side of the frame and of one of the dies I.

Figure 3 is a front view of the face of the guide-wheel or gear G, and of the other die K.

Figure 4 is a. perspective view of the spring N attached to the hub H for throwing out the screw when the thread is formed.

Figure 5 is a perspective view of the guides M M, which are attached to the guide-wheel G to keep the blank in position while being operated on.

A A is the frame, figs. 1 and 2. B B B B are bars or rods for holding the frame together, by means of the screws thereon, and the nuts I: b b b, fig. 1. O is the driving-shaft, fig. 1. D, fig. 1, is a stpd-gear thereon,- which drives E, fig. 1, a like stud-gear, and of the same diameter and number of teeth, which is attached to and revolves with F, another studgear, which revolves on B, fig. 1. G is a guide-wheel or gear driven by F, figs. 1 and 3. H is a hub, attached to the driving-shaft; C, figs. 1 and 4. The guide-wheel G revolves on a projection of H, and surrounds the hub H on all sides but its face, on which face is placed the die K, fig. 1. I is the stationary die attached to the inside of the frame A, figs. 1 and.2.- I is the toothed portion of I, figs. 1 and 2. I is the plane face of I, figs. 1 and 2. K is the rotating die-on the face of H, figs. 1 and 3. is a hole or depression in the face of G, figs. 1 and 3, to allow the head and shank of the blank to rest in while being operated on. M is a guide, and M a set-screw for keeping the blank in position while being operated on, figs. 1 and 5. N, figs. 3 and 4, is a spring for throwing out the screw when the thread has been formed. 0 is a. nut for regulating the pressure of the dies I and K, fig. 1.

The frame may be of two stout metallic plates, something in the form of a broad X, held together by four stout bolts B B B B", with screws and nuts I; 6 b b, as seen in figs. 1 and 2.

The driving-shaft O passes through the centres of the frames A A and rotates the die K, as well as indirectly the guide-wheel G; K making two revolutions to every one of This is effected as follows: The gear D is attached to the driving-shaft C, as is also the hub H to which K is attached, and consequently both have the same motion. D gears into E, having the some diameterand number of teeth, and is attached to F and turns it, while F gears into C, which hasjust double the number of teeth of F. 'Hence, while the hub H and attached disk K have the motion of the shaft O, G, which revolves around the hub H, has one-half its speed.

The reason for having one move twice as fast as the other, is this: the head and shank of the blank are placed in a hole or depression, L, figs. 1 and 3, in the face of the guide-wheel G, while it is made to roll by the movement of the two dies I and K. On the rule stated the die K mu'stmove at its circumference twice as fast as the blank moves, and consequently twice as fast as G moves, and by this relative speed the blank is kept in position during the time the thread is being formed. I

The dies I and K are two similarly-formed fiat steel rings, figs. 1, 2, and 3, of suflicient strength to bear the pressure on them in forming the thread of the screw, and of sufiicient width to allow for the necessary number of teeth and for attaching it to the frame A or hub H. Or instead of being rings they may be segments of circles, each segment being of sufficient length to complete the thread of one screw. The face of each die, on its outer edge, is cut away, figs. 1, 2, and 3, for about the proposed length of the threaded part of the screw. On this depressed part of each die is cut a series of grooves, leaving a set of raised teeth; the grooves and teeth each extending from the outer edge of the plain surface of the die to the outer edge of the die, and

having a curvenomcwhat' in the form of a. part of the involute of a small circle, as seen in figs. 2 and 3, but which curve. will be bet-tor determined, practically, by rolling over the face of the die, before cut, a screw of the proposed thread having its point always directed towards the centre and its axis in the direction of the radius while being so rolled. The screw thus rolled will leave impressed on the surface of the die, if covered with some soft substance, the curve and position of the required grooves and teeth to form a similar screw.

The depressed parts of the dies slope downward towards the outer edges, slightly, and the grooves are deeper towards the inner edge than towards the outer edges of the dies, by means of which the thread is formed somewhat deeper towards the point than towards the shank. The'grooves and teeth are also very slight at the commencement and increase in depth towards the end of the die or segment. This enables the die to take hold more readily at first and to form the thread more easily. There must be a space between the end of the dies, or a, portion of the dies must be cut away, as seen in figs. 2 and 3, to allow the blanks to be inserted, and to drop out when finished.

To keep the blanks in position and place, while being operated on, the guides M and set-screw M, fig. 5, are attached to the face of the guide-wheel G. The guides M are thin circular plates, of as many segments as it is proposed to make screws at each revolution of the guide-wheel G. Two ends are placed over the hole In in the. face of Gr, at such distance apart as to allow a screw tov lie between them when in place, there being notches in each end to allow the head of the screw to pass into the hole L. The inner edges of M are tapered, and when in place they project in between the teeth of the (lies I and K, as seen in fig. 1. The purpose of the guides is to keep the blank always parallel to the radius of the dies. To keep the blank down aset-screw, M, is placed over the head of the blank, as seen in fig. 5; or it may be inserted in the periphery of the wheel G, as seen in figs. 1 and 3.

The spring N, figs. 3 and 4, serves to throw out the screw when completed. It is a flat piece of steel, and is so bent and attached to the hub H that one part of its upper end presses against the plane surface of the die I.

The male not 0, fig. 1, is for the purpose of regulating the pressure of the dies I and K. By screwing in the nut it will press on the end of the shaft C, and the die K will be pressed against 1. Unscrewing the not of course releases the pressure.

The mode of operation of the machine, as described, is as follows: A blank is placed in the space between the ends of the guides M M, with the head in the hole L in the face of G, as seen in figs. 1, 3, and 5. The shaft 0 is then turned, and the dies I and K take hold of the lower end of the-blank and give to it a rotary motion, while the guides M M and set-screw M keep it in true position. As the die K has an angular motion twice that of G, and consequently of the blank, the die K soon passes over the bla'nk and completes the thread, when the spring N, at the opposite end of K, forces out the screw.

This form of machine, and operated as described, forms two threads on each screw. A part of the teeth of the wheel G may be reduced about one-half to one-third in thickness, which will tend to prevent the guides M M from pressing too closely on thethreads of the screw. This reduction of the thickness of the teeth may commence, say about one-eighth of the periphery from the point where the blank is inserted, and be carried round, say, from four-eighths to five-eighths of the remainder of the periphery.

The machine may be moved by power, and the blanks fed continuously in any of the well-known ways for such purpose. v

The guide-wheel and guides are not absolutely essential, but their use keeps the blank more true in position, and renders the thread more perfect and uniform.

The dies and guides may be formed in sections, so that two or more blanks may be inserted at proper distances apart, and all be operated on at the same time. Instead of making the die I stationary, it may be made to revolve in a. direction different from that of K, by suitable gearing in any of the well-known ways for effecting such a purpose. I And instead of making the dies operate by their faces, as described, they may be made to operate upon their peripheries; that is, the die may be cut on the convex surface of a circular die, and the other on the concave surface of another concentric to it; or the outer die may be formed in segments, and time as many screws may be formed as there are segments. In this mode the screws will drop out without the intervention of a spring or other contrivance; and the pressure of the dies may be regulated by screws or any other known contrivance for such purpose. v

There may also be another modification of the invention. Three spindle formed dies may be used, converging towards :1 point, around the lower ends of which the teeth may be out, having suitable gearing to give them the proper rotary motion. In this case the screw may be dropped in between the dies from above, and when the thread is completed the dies may be made to open by cams or other well-known mechanical movements,. sufficiently to allow it to drop out while another blank would take its place.

And there may be a modification of this last-form of the invention, in which the operation of inserting and withdrawing the blank would be reversed; that is, the blank would be inserted from below, with its point u ward, and when the thread would be finished, be allowed to drop out by the opening of the dies, as before mentioned. i

The dies also may be reciprocating instead of rotatry, in which case the screw will drop out when completed. In this case the grooves and teeth of the dies will be diagonal lines, without curves. The form and position of the grooves and teeth in this case, and in all the others mentioned, may be determined practically, as before described, by rolling over the surface of the die a screw of the desired size in the direction the blank will roll when being operated on. v

Screws made in the manner described are much stronger than those made by cutting; and having a double thread they operate more readily than the gimlet-pointed screw, while the thread holds its entire length, and not merely at the upper part, as with the gimlet-pointcd screw.

The machine is much simpler than any other form. But the advantage of this improvement consists mainly in the greater rapidity with which the thread may he formed.

I do not claim broadly as my invention, milling or impressing figures on blanks by rotating or other dies; nordo I claim the formation of the thread of screws by percussion or blows in dies; but I do claim- 1. The combination of the dies I and K, and the guides M M, constructed and operating substantially as described and for the uses and purposes mentioned. i

2. The combination of the said dies and guides and the set-screw M, oonstruetedsnd operating substantially as described and for-the uses and purposes mentioned.

A HARVEY J. HARWOOD.

Witnesses:

' HENRY GREEN,

JOHN G. Onocxnn. 

